I have a table as UserData which has strucure like
id category value
1 AR 100
2 WT 90
3 WT 12
4 AR 1000
5 AR 2005
6 WT 122
7 BP 112
8 BP 18
now I want to select all rows which has maximum value in the indiviual category. so my result set should be.
id category value
5 AR 2005
6 WT 122
7 BP 112
I want to have this in both MongoDB and SQL server query.
In SQL I tried this
select id,category,value from
(select id,
category,
value,
max(value)
over (partition by category) result
from UserData ) a
where a.result=a.value order by a.id
this is giving me desired result but somehow I feel that it is not good
so I want a better solution for this in SQL and corresponding equivalent solution for MongoDB
I'm not sure about a mongo solution, but if you don't care about Id - here is the way to get the highest value for a category.
SELECT DISTINCT
Category, MAX(Value)
FROM UserData
GROUP BY category
Excuse me if this is more simplistic than what you desire.
Related
I have a query which I like to use for paging. With dapper I am able to take the query below and use SplitOn which allows me to separate the results on the left side of SplitOn column into one object and results of the right side of SplitOn column into a second object. What this allows me to do is get a total records count along with records for "specified" pages only
SELECT *
FROM (
SELECT
*,1 as SplitOn,
(ROW_NUMBER() OVER(ORDER BY Id )) AS RowNum, COUNT(*) over() as TotalRows
FROM (
SELECT Id, FirstName, LastName FROM Customer
) AS FirstQuery
) AS TEMP
WHERE RowNum BETWEEN 1 + ((#Page - 1) * #PageSize) AND #Page * #PageSize
If you run above in SQL for page 6 you will get:
Id FirstName LastName SplitOn RowNum TotalRows
61 John Luke 1 1 120
62 Jane Sky 1 2 120
63 Boby Doe 1 3 120
64 Sam Ace 1 4 120
65 Dany Table 1 5 120
etc...
I am trying to accomplish the same with EF6 but I cannot for the life of me figure out how to convert that query to an equivalent LinQ Expression.
I realize that SplitOn may not be possible with EF6, so I can work around that with a single object, but I still cannot figure out how to make my query with LinQ.
I have the following query to count how many times each process_track_id occurs in a table:
SELECT
a.process_track_id,
COUNT(1) AS 'num'
FROM
transreport.process_name a
GROUP BY
a.process_track_id
This returns the following results:
process_track_id | num
1 14
2 44
3 16
5 8
6 18
7 17
8 14
This is great. Now is the part where I am stuck. I would like to get the following table:
num count
8 1
14 2
16 1
17 1
18 1
44 1
Where num are the distinct counts from the first table, and count is how many times that frequency occurs.
Here is what I have tried (it's a subquery, but I'm not sold on the method) and I haven't been able to get it to work just yet. I'm new to SQL and I think I'm missing out on some some key aspects of the syntax.
SELECT
X.id_count,
count(1) as 'num_count'
FROM
(SELECT
a.process_track_id,
COUNT(1) AS 'id_count'
FROM
transreport.process_name a
GROUP BY
a.process_track_id
--COUNT(1) AS 'id_count'
) X;
Any ideas?
It's probably good to keep in mind that this may have to be run on a database with at least 1 million records, and I don't have the ability to create a new table in the process.
Thanks!
Here's the subquery method you were driving at:
SELECT id_count, COUNT(*) AS 'num_count'
FROM (SELECT a.process_track_id
,COUNT(*) AS 'id_count'
FROM transreport.process_name a
GROUP BY a.process_track_id
)sub
GROUP BY id_count
Not sure there's a better method as the aggregation needs to run once anyway.
Try this
SELECT x.num, COUNT(*) AS COUNT
FROM (
SELECT
a.process_track_id, -- <--- You may removed this column
COUNT(*) AS 'num'
FROM
transreport.process_name a
GROUP BY
a.process_track_id
) X
GROUP BY X.num
This question already has answers here:
How to get rows having sum equal to given value
(4 answers)
Closed 9 years ago.
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here is table T :-
id num
-------
1 50
2 20
3 90
4 40
5 10
6 60
7 30
8 100
9 70
10 80
and the following is a fictional sql
select *
from T
where sum(num) = '150'
the expected result is :-
(A)
id num
-------
1 50
8 100
(B)
id num
-------
2 20
7 30
8 100
(C)
id num
-------
4 40
5 10
8 100
the 'A' case is most preferred !
i know this case is related to combinations.
in real world - client gets items from a shop, and because of an agreement between him and the shop, he pay every Friday. the payment amount is not the exact total of items
for example: he gets 5 books of 50 € ( = 250 € ), and on Friday he bring 150 €, so the first 3 books are perfect match - 3 * 50 = 150. i need to find the id's of those 3 books !
any help would be appreciated!
You can use recursive query in MSSQL to solve this.
SQLFiddle demo
The first recursive query build a tree of items with cumulative sum <= 150. Second recursive query takes leafs with cumulative sum = 150 and output all such paths to its roots. Also in the final results ordered by ItemsCount so you will get preferred groups (with minimal items count) first.
WITH CTE as
( SELECT id,num,
id as Grp,
0 as parent,
num as CSum,
1 as cnt,
CAST(id as Varchar(MAX)) as path
from T where num<=150
UNION all
SELECT t.id,t.num,
CTE.Grp as Grp,
CTE.id as parent,
T.num+CTE.CSum as CSum,
CTE.cnt+1 as cnt,
CTE.path+','+CAST(t.id as Varchar(MAX)) as path
from T
JOIN CTE on T.num+CTE.CSum<=150
and CTE.id<T.id
),
BACK_CTE as
(select CTE.id,CTE.num,CTE.grp,
CTE.path ,CTE.cnt as cnt,
CTE.parent,CSum
from CTE where CTE.CSum=150
union all
select CTE.id,CTE.num,CTE.grp,
BACK_CTE.path,BACK_CTE.cnt,
CTE.parent,CTE.CSum
from CTE
JOIN BACK_CTE on CTE.id=BACK_CTE.parent
and CTE.Grp=BACK_CTE.Grp
and BACK_CTE.CSum-BACK_CTE.num=CTE.CSum
)
select id,NUM,path, cnt as ItemsCount from BACK_CTE order by cnt,path,Id
If you restrict your problem to "which two numbers add up to a value", the solution is as follows:
SELECT t1.id, t1.num, t2.id,t2.num
FROM T t1
INNER JOIN T t2
ON t1.id < t2.id
WHERE t1.num + t2.num = 150
If you also want the result for three and more numbers you can achieve that by using the above query as a base for recursive SQL. Don't forget to specify a maximum recursion depth!
To find the id's of the books that the client is paying, you would need to have a table with your clients, and another one to store the orders of the client, and what products he bought.
Otherwise it would be impossible to know what product the payment refers to.
This question already has answers here:
Fetch the rows which have the Max value for a column for each distinct value of another column
(35 answers)
Closed 2 years ago.
I'm working with a table that has about 50 colums and 100,000 rows.
One column, call it TypeID, has 10 possible values:
1 thourgh 10.
There can be 10,000 records of TypeID = 1, and 10,000 records of TypeID = 2 and so one.
I want to run a SELECT statement that will return 1 record of each distinct TypeID.
So something like
TypeID JobID Language BillingDt etc
------------------------------------------------
1 123 EN 20130103 etc
2 541 FR 20120228 etc
3 133 FR 20110916 etc
4 532 SP 20130822 etc
5 980 EN 20120714 etc
6 189 EN 20131009 etc
7 980 SP 20131227 etc
8 855 EN 20111228 etc
9 035 JP 20130615 etc
10 103 EN 20100218 etc
I've tried:
SELECT DISTINCT TypeID, JobID, Language, BillingDt, etc
But that produces multiple TypeID rows of the same value. I get a whole bunch of '4', '10', and so on.
This is an ORACLE Database that I'm working with.
Any advise would be greatly appreciated; thanks!
You can use ROW_NUMBER() to get the top n per group:
SELECT TypeID,
JobID,
Language,
BillingDt,
etc
FROM ( SELECT TypeID,
JobID,
Language,
BillingDt,
etc,
ROW_NUMBER() OVER(PARTITION BY TypeID ORDER BY JobID) RowNumber
FROM T
) T
WHERE RowNumber = 1;
SQL Fidle
You may need to change the ORDER BY clause to fit your requirements, as you've not said how to pick one row per TypeID I had to guess.
WITH RankedQuery AS
(
SELECT *,
ROW_NUMBER() OVER (PARTITION BY TypeID ORDER BY [ordercolumn] DESC) AS rn
FROM [table]
)
SELECT *
FROM RankedQuery
WHERE rn = 1;
This will return the top row for each type id, you can add an order by if you want a specific row, not just any.
I have a sql / sqlite question. I need to write a query that select some values from a sqlite database table. I always want the maximal returned records to be 20. If the total selected records are more than 20 I need to select 20 records that are spread evenly (no random) over the total records. It is also important that I always select the first and last value from the table when sorted on the date. These records should be inserted first and last in the result.
I know how to accomplish this in code but it would be perfect to have a sqlite query that can do the same.
The query Im using now is really simple and looks like this:
"SELECT value,date,valueid FROM tblvalue WHERE tblvalue.deleted=0 ORDER BY DATE(date)"
If I for example have these records in the talbe and to make an easier example the maximum result I want is 5.
id value date
1 10 2010-04-10
2 8 2010-04-11
3 8 2010-04-13
4 9 2010-04-15
5 10 2010-04-16
6 9 2010-04-17
7 8 2010-04-18
8 11 2010-04-19
9 9 2010-04-20
10 10 2010-04-24
The result I would like is spread evenly like this:
id value date
1 10 2010-04-10
3 8 2010-04-13
5 10 2010-04-16
7 8 2010-04-18
10 10 2010-04-24
Hope that explain what I want, thanks!
Something like this should work for you:
SELECT *
FROM (
SELECT v.value, v.date, v.valueid
FROM tblvalue v
LEFT OUTER JOIN (
SELECT min(DATE(date)) as MinDate, max(DATE(date)) as MaxDate
FROM tblvalue
WHERE tblvalue.deleted = 0
) vm on DATE(v.date) = vm.MinDate or DATE(v.date) = vm.MaxDate
WHERE tblvalue.deleted = 0
ORDER BY vm.MinDate desc, Random()
LIMIT 20
) a
ORDER BY DATE(date)
I think you want this:
SELECT value,date,valueid FROM tblvalue WHERE tblvalue.deleted=0
ORDER BY DATE(date), Random()
LIMIT 20
In other words you want select rows with date column, so that date is from the sorted list of dates, from where we take every odd element? And add the last recorded element (with the latest date)? And everything limited to max 20 rows?
If that's the case, then I think this one should do:
SELECT id,value,date FROM source_table WHERE date IN (SELECT date FROM source_table WHERE (rowid-1) % 2 = 0 OR date = (SELECT max(date) FROM source_table) ORDER BY date) LIMIT 20